A solar cell using sunlight has become a focus of attention as an energy resource alternative to fossil fuel such as petroleum or coal. At present, a silicon solar cell using crystalline or amorphous silicon, a compound semiconductor solar cell using gallium, arsenic, etc., and the like have vigorously been studied and developed. However, since a large amount of energy and high cost are required for production of such solar cells, they are problematic in terms of difficulty in generally using such solar cells. On the other hand, a photoelectric conversion device using semiconductor fine particles sensitized with a dye, and a solar cell using such a photoelectric conversion device have also been known. Materials used in production of such products and production techniques have been disclosed (see Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2). This photoelectric conversion device is produced using relatively inexpensive oxide semiconductors such as titanium oxide. There is a possibility that this photoelectric conversion device can be produced at a cost lower than that of a conventional solar cell using silicon or the like. Moreover, this photoelectric conversion device has become a focus of attention because more colorful solar cells can be obtained using it. However, in order to obtain a device with high conversion efficiency, a ruthenium complex is used as a sensitizing dye, and such a dye is expensive. Further, a problem remains also in terms of the supply of such a dye. Furthermore, an attempt has already been made to use an organic dye as such a sensitizing dye. However, such a photoelectric conversion device using an organic dye has been poor in terms of conversion efficiency, stability and durability, and thus, it has not yet been in practical use under the current circumstances. It has been desired to further improve such conversion efficiency (see Patent Documents 2 and 3). Still further, with regard to the photoelectric conversion device of the present invention, attempts such as consolidation of an electrolyte have also been made (see Non-Patent Document 3), and thus, the development of a device with excellent durability has been required.
Patent Document 1: Japanese Patent No. 2664194
Patent Document 2: WO2002/011213
Patent Document 3: WO2004/082061
Non-Patent Document 1: B. O'Regan and M. Graetzel, Nature, Vol. 353, p. 737 (1991)
Non-Patent Document 2: M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Muller, P. Liska, N. Vlachopoulos, M. Graetzel, J. Am. Chem. Soc., Vol. 115, p. 6382 (1993)
Non-Patent Document 3: W. Kubo, K. Murakoshi, T. Kitamura, K. Hanabusa, H. Shirai, and S. Yanagida, Chem. Lett., p. 1241 (1998)
It has been desired to develop a photoelectric conversion device using oxide semiconductor fine particles sensitized with an organic dye, wherein an inexpensive organic dye is used to produce a photoelectric conversion device with stability, high conversion efficiency and high feasibility.